Headshakers

It’s normal for horses to shake to relieve the irritation of flies.

Horses shaking their heads is quite normal. Horses need to get rid of annoying flies, which they can do by a rippling effect of the panniculus muscles on their flanks, tail swishing, foot stamping or headshaking.

However, chronic headshaking is a different story. It takes on a whole new meaning when this behaviour is performed frequently, if not constantly, mainly while the horse is being ridden. This is not normal behaviour. Headshaking is a sign of severe stress or neurological disease, and the horse usually cannot be ridden safely.

What causes headshaking?

Many theories have been put forward to suggest the reason for this strange behaviour. Headshakers can demonstrate anything from a slight tic to distressed jerking of the head. Let’s take a closer look at some of the more common theories.

Headshaking can be caused by damage to a sensory nerve in the face (eyes, teeth, sinuses, nasal cavity). Triggering of the sensory nerve endings, through touch, heat or cold, moisture or dryness, can cause the brain to respond to the trigger through headshaking.

In rare cases, a horse can develop headshaking after a severely traumatic or distressing experience. A very small portion of horses who have suffered such an experience become headshakers, but sometimes the effects are so bad that it turns into a permanent problem.

Chronic headshaking usually stops in the winter months. It also stops in complete darkness. It does not occur in feral horses, nor when a horse is galloping. In most cases, there is no chronic headshaking while the horse is not working, such as during the time spent being turned out in the field. The quick movement of the head to shake off flies is perfectly normal. So, is there a connection between the normal and the abnormal behaviour? The horse knows when there are no flies around, when it is cold, when it is dark, or when he is at a gallop.

Another triggering factor

Some horses who are overly sensitive in their faces don’t like the feeling of tack on their head.

The last factor to be researched is more challenging: why does abnormal headshaking start up when the horse starts working and what change takes place at this stage to cause the headshaking?

The change is exactly the same as in humans. During work activity, the blood pressure rises. Ordinarily, this should not cause a problem, but domesticated horses naturally have intermittent times of work and rest. This pattern can cause some sweat ducts to block, particularly on the face where the skin is very sensitive. In these horses, when strenuous activity starts, the blood pressure makes the face feel prickly, like a fly strike, and so there is continuous headshaking.

Some horses who are overly sensitive in their faces don’t like the feeling of tack on their heads. They shake their heads to try and relieve themselves of the feeling. In these cases, the rider can try removing certain pieces such as the browband or noseband and see if that makes a difference. Special poll pieces that are cut further back or better padded can also make a difference.